If you sleep for less than 5 hours, your heart will become weaker and will suffer a lot. Even if you sleep for less than 7 hours, you will go through severe health problems and your body will be prone to weight-loss and diabetes.
The advice here is that you should sleep well and let your body relax and your body will thank-you in form of energy and power of mind that it supplies.
Charles Czeisler, a professor at Harvard University, along with his team of several experts conducted many experiments to study sleep patterns and sleep disorders and the effects of sleeplessness on human body. He found out many amazing facts about the importance of sleep.